The present invention relates to a thin-film magnetic head provided with at least an inductive recording transducer element and a method of manufacturing the head.
Recently, demand for higher recording density has made a recording track width narrower, and therefore a submicron width of the pole of the recording head part has been needed. To cope with such narrower pole width, a thin-film magnetic head is formed in a manner that only the recording pole portion is separated from other portions. That is, a three-layer pole tip structure with a lower pole tip element, a recording gap layer and an upper pole tip element is formed at only a pole tip region located between an air bearing surface (ABS) and a position at a predetermined height from the ABS in the recording head part, and an upper yoke and a lower yoke are magnetically connected to the top surface and the bottom surface of this pole tip structure, respectively.
FIG. 1 is a schematic ABS view, illustrating an example of a conventional composite type thin-film magnetic head with an inductive recording head part and a magnetoresistive (MR) reproducing head part.
In the figure, the reference numeral 10 denotes a lower shield layer of the MR reproducing head part, 11 denotes an upper shield layer of the MR head part, which also acts as a lower auxiliary pole of an inductive recording head part, 12 denotes a MR layer provided through an insulating layer 13 between the lower shield layer 10 and the upper shield layer 11, 14 denotes a lower pole tip element of the inductive recording head part, 15 denotes an upper pole tip element, 16 denotes a recording gap layer formed between the lower and upper pole tip elements 14 and 15, 17 denotes an insulating layer deposited on the upper shield layer 11 and around a three-layer pole tip structure consisting of the lower pole tip element 14, the recording gap layer 16 and the upper pole tip element 15, and 18 denotes an upper auxiliary pole formed on the insulating layer 17 and deposited to contact with the upper pole tip element 15. The upper auxiliary pole 18 is magnetically connected with the lower auxiliary pole (upper shield layer) 11 at its rear portion so as to constitute a magnetic yoke together with the lower auxiliary pole 11.
The head with the three-layer pole tip structure shown in FIG. 1 can realize a narrower track width. However, peeling is liable to occur at the interface between the upper pole tip element 15 and the upper auxiliary pole 18 which are located at the trailing side and act an important role during recording. Also, since the three-layer pole structure has a narrow pole width of submicron, the magnetic domain, i.e. the easy magnetization axis, directs to a longitudinal direction of the poles causing the recording current to magnetic field conversion efficiency to lower.
FIG. 2 is a schematic ABS view illustrating another example of a conventional composite type thin-film magnetic head having a three-layer pole structure, described in U.S. Pat. No. 5,452,164, and FIG. 3 is a cross-sectional view perpendicular to the plane of the ABS, illustrating the example of FIG. 2.
In FIG. 2, the reference numeral 20 denotes a lower shield layer of the MR reproducing head part, 21 denotes an upper shield layer of the MR head part, which also acts as a lower auxiliary pole of an inductive recording head part, 22 denotes a MR layer provided through an insulating layer 23 between the lower shield layer 20 and the upper shield layer 21, 24 denotes a lower pole tip element of the inductive recording head part, 25 denotes an upper pole tip element, 26 denotes a recording gap layer formed between the lower and upper pole tip elements 24 and 25, 27 denotes a lower insulating layer deposited on the upper shield layer 21 and around a three-layer pole structure consisting of the lower pole tip element 24, the recording gap layer 26 and the upper pole tip element 25, 28 denotes an upper auxiliary pole, 29 denotes a coil conductor formed on the lower insulating layer 27, and 30 denotes an upper insulating layer covering the coil conductor 29, respectively. In this example, the three-layer pole tip structure protrudes from the upper surface of the lower insulating layer 27 at a region near the ABS. The upper auxiliary pole 28 is formed to cover the protruded portion of the upper pole tip element 25 of the pole tip structure. This upper auxiliary pole 28 is magnetically connected with the lower auxiliary pole (upper shield layer) 21 at its rear portion so as to constitute a magnetic yoke together with the lower auxiliary pole 21.
However, according to the conventional structure shown in FIGS. 2 and 3, the top of the lower insulating layer 27 at a region on which the coil conductor 29 is formed, which is far from the ABS, is formed so that it is certainly higher than the top of the three-layer pole tip structure. Thus, it is difficult to efficiently release heat generated by the recording current flowing through the coil conductor 29. In general, it is necessary that heat from the coil conductor 29 is released outward via a metal member to enhance the reliability of the magnetic head. However, because the upper auxiliary pole 28 has small volume, it is insufficient to radiate the heat. In addition, because the lower insulating layer 27 is thick at this region under the upper auxiliary pole 28, it is difficult to efficiently transmit the heat to the upper shield layer 21.
Furthermore, because of the aforementioned conventional structure in which height in the top of the upper pole tip element 15 is the same as that of the insulating layer 17, peeling often occurs at the interface between the upper pole tip element 15 and the upper auxiliary pole 18.
Also, the conventional method for manufacturing the three-layer pole tip structure shown in FIGS. 2 and 3 causes its fabricating processes to be very complicated.
It is therefore an object of the present invention to provide a thin-film magnetic head and a method of manufacturing the head, whereby decrease in reliability derived from generation of heat can be effectively prevented.
Another object of the present invention is to provide a thin-film magnetic head and a method of manufacturing the head, whereby peeling at the interface between the upper pole tip element and the upper auxiliary pole can be prevented.
Further object of the present invention is to provide a thin-film magnetic head and a method of manufacturing the head, whereby manufacturing processes can be simplified.
According to the present invention, a thin-film magnetic head having an air bearing surface, includes a three-layer pole tip structure consisting of a lower pole tip element, a recording gap layer and an upper pole tip element, the structure having side surfaces, a rear surface and top surface, a lower auxiliary pole, a part of which contacts to the lower pole tip element, an upper auxiliary pole, a part of which contacts to the upper pole tip element, the upper auxiliary pole being magnetically connected at its rear portion with respect to the air bearing surface to the lower auxiliary pole so as to form a yoke together with the lower auxiliary pole, a lower insulating layer, surrounding the side surfaces and the rear surfaces of the three-layer pole tip structure, the lower insulating layer being located between the lower and upper auxiliary poles and having a top surface, a coil conductor formed on the top surface of the lower insulating layer, and an upper insulating layer covering the coil conductor, a part of the upper insulating layer being located between the lower insulating layer and the upper auxiliary pole. The top surface of the lower insulating layer is leveled lower than the top surface of the three-layer pole tip structure over at least a region within which the coil conductor is formed.
Since the top surface of the lower insulating layer on which the coil conductor is formed is constructed in a level lower than the top surface of the upper pole tip element, the lower insulating layer itself can be made as a thin layer. As a result, heat generated from the coil conductor can be easily transmitted to the lower auxiliary pole arranged below the coil conductor. In particular, since the lower auxiliary pole has a large area and the lower insulating layer is made thin, the heat dispersion effects are increased, whereby generation of heat from a magnetic head can be effectively prevented.
It is preferred that the top surface of the lower insulating layer is formed in flat over its entire surface.
It is also preferred that the top surface of the lower insulating layer is leveled lower than the top surface of the three-layer pole tip structure over its entire surface.
It is preferred that a part of the upper pole tip element is protruded from the top surface of the lower insulating layer, and that the upper auxiliary pole is fixed to the part of the upper pole tip element so as to cover the part of the protruded upper pole tip element.
It is also preferred that a level difference between the top surface of the lower insulating layer adjacent to the three-layer pole tip structure and the top of the three-layer pole tip structure is 25 nm or more.
Preferably, the thin-film magnetic head is a composite type thin-film magnetic head with a MR reproducing head part having a lower shield layer, an upper shield layer and a MR layer formed between the lower and upper shield layers through an insulating layer, and the upper shield layer also acts as the lower auxiliary pole.
According to the present invention, also, a method of manufacturing a thin-film magnetic head includes the step of forming, on a lower auxiliary pole, a three-layer pole tip structure consisting of a lower pole tip element, a recording gap layer and an upper pole tip element, the step of depositing a lower insulating layer on the three-layer pole tip structure, the step of polishing the lower insulating layer by chemical-mechanical polishing (CMP) so that a top surface of the lower insulating layer is leveled lower than a top of the three-layer pole tip structure over at least a region within which a coil conductor is formed, the step of forming the coil conductor on the lower insulating layer, the step of forming an upper insulating layer to cover the coil conductor, and the step of forming an upper auxiliary pole so that a part of which contacts to the upper pole tip element.
After forming the lower insulating layer on a three-layer pole tip structure, this lower insulating layer is polished by a CMP process so that the top surface of the lower insulating layer is in a level lower than the top surface of the three-layer pole tip structure (the top surface of the upper pole tip element) over at least a region within which a coil conductor is formed. Thus, by only polishing using CMP process, the upper pole tip element of the three-layer pole tip structure is upward protruded from the lower insulating layer and the top surface of the lower insulating layer is in a level lower than the top surface of the three-layer pole tip structure over at least a region within which a coil conductor is formed, causing the manufacturing processes to be very simplified.
It is preferred that the polishing step includes the step of polishing so that the top surface of the lower insulating layer is formed in flat over its entire surface.
It is also preferred that the polishing step includes the step of polishing so that the top surface of the lower insulating layer is leveled lower than the top surface of the three-layer pole tip structure over its entire surface.
It is preferred that the polishing step includes the step of polishing so that a part of the upper pole tip element is protruded from the top surface of the lower insulating layer, and that the upper auxiliary pole forming step includes the step of forming the upper auxiliary pole to fix to the part of the upper pole tip element so as to cover the part of the protruded upper pole tip element.
Preferably, the method further includes the step of forming a lower shield layer, the step of forming a MR layer on the lower shield layer, and the step of forming an upper shield layer on the MR layer through an insulating layer, the upper shield layer acting also as the lower auxiliary pole.